Heart valve disease continues to be a significant cause of morbidity and mortality, resulting from a number of ailments including rheumatic fever and birth defects. Recent statistics show that valvular heart disease is responsible for nearly 20,000 deaths each year in the United States, and is a contributing factor in approximately 42,000 deaths. Currently, the primary treatment of aortic valve disease is valve replacement. Worldwide, there are approximately 300,000 heart valve replacement surgeries performed annually.
Coronary artery disease also remains a leading cause of morbidity and mortality and manifests in a number of ways. For example, disease of the coronary arteries can lead to insufficient blood flow resulting in the discomfort and risks of angina and ischemia. In severe cases, acute blockage of coronary blood flow can result in myocardial infarction, leading to immediate death or damage to the myocardial tissue.
A number of interventional approaches have been developed for treating heart valve and coronary artery disease. For instance, annuloplasty rings have been developed in various shapes and configurations over the years to correct mitral regurgitation and other conditions which reduce the functioning of the valve. Heart valve replacement may be indicated when there is a narrowing of a native heart valve, commonly referred to as stenosis, or when the native valve leaks or regurgitates, such as when the leaflets are calcified. When replacing the valve, the native valve may be excised and replaced with either a biologic or a mechanical valve. Coronary blockage can often be treated endovascularly using techniques such as balloon angioplasty, atherectomy, or stents.
Most interventional techniques are conducted under general anesthesia and require that the patient's sternum be opened and the chest be spread apart to provide access to the heart. The first 2-3 days following surgery are spent in an intensive care unit where heart functions can be closely monitored. The average hospital stay is between 1 to 2 weeks, with several more weeks to months required for complete recovery. While often very effective, the use of open-heart surgery to perform cardiac procedures is a highly traumatic to the patient.
Recently, minimally invasive surgical techniques and procedures to perform coronary artery bypass grafting (CABG) and other traditionally open-chest cardiac surgical procedures are gaining acceptance. A wide variety of laparoscopic, arthroscopic, endovascular, and other surgical therapies have been developed. These procedures generally utilize trocars, cannulas, catheters, or other tubular sheaths to provide an artificial lumen, through which specialized tools are inserted and manipulated by the surgeon.
Some researchers propose implanting prosthetic heart valves at the aortic annulus using a direct-access transapical (through the left ventricular apex) approach (e.g., U.S. Patent Publication No. 2006-0074484). The left ventricular apex LVA is directed downward, forward, and to the left (from the perspective of the patient). The apex typically lies behind the fifth left intercostal space (or between the fourth and fifth), 8 to 9 cm from the mid-sternal line, and about 4 cm below and 2 mm to the medial side of the left mammary papilla. Access to the left ventricle may therefore be attained through an intercostal incision positioned over the fifth left intercostal space. Such an approach is often termed a “mini-thoracotomy,” and lends itself to surgical operations on the heart carried out using one or more short tubes or “ports”—thus, the operations are often referred to as “port-access” procedures. Such direct-access or “port access” techniques though less invasive than conventional open heart surgery are not called “minimally-invasive,” as that term is now primarily used to refer to valves delivered using elongated catheters via the vasculature (i.e., endovascularly).
Dehdashtian in U.S. Patent Publication No. 2007-0112422 discloses a port-access delivery system for transapical delivery of a prosthetic heart valve including a balloon catheter having a steering mechanism thereon that passes through an access device such as an introducer. The surgeon forms a puncture in the apex with a needle, advances a guidewire, then a dilator, and finally the introducer. Edwards Lifesciences sells the Sapien™ Heart Valve that may be inserted transapically with the Ascendra™ delivery system, much like the system disclosed in Dehdashtian.
Often, direct- or port-access techniques are conducted or proposed for off-pump, or beating heart procedures. The advantages of eliminating open-heart procedures and cardiopulmonary bypass are evident. Challenges remain in stabilizing various instruments used during these procedures. For example, a number of devices are available that directly contact the heart muscle for stabilizing an area around a cardiac artery for CABG procedures, most notable the OCTOPUS and URCHIN devices from Medtronic, and ACROBAT and XPOSE devices from Maquet. These systems typically include a soft contact member having suction that brackets a coronary artery, or grabs and manipulates an area of the heart for better access. These systems are mostly concerned with holding still a discrete surface area of the heart for direct operation thereon, and are not designed for operations carried out by instruments that extend within the beating heart, i.e., for intracardiac procedures.
In view of drawbacks associated with previously known techniques for stabilizing certain port-access procedures, improved methods and apparatuses are needed.